Total Synthesis of the Proposed Structure of Ardimerin, and Proposal for its Structural Revision

We report the first total synthesis of the proposed structure of ardimerin, which was achieved in 14 steps starting from 2,3,4-trimethoxybenzoic acid. The key steps include the beta-selective formation of the crucial C-glycoside linkage and stepwise construction of the strained eight-membered salicylide core. The synthesis revealed that the proposed structure 1 does not match the natural product. A proposal is made for reassigning the isolated natural product to the already known structure of bergenin. Interesting properties of the synthetic eight-membered salicylides are documented, including their susceptibility toward nucleophilic ring opening and the bowl chirality.